/ Dictionary / Index P picosecond: Meaning and Definition of Find definitions for: pi•co•sec•ond Pronunciation: (pē'ku-sek"und, pī'-), [key] — n. one trillionth of a second. Abbr.: ps, psec Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: picosecond (Thesaurus) picornavirus picot Related Content Daily Word Quiz: deleterious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language